Windshield wiper fluid comes in gallon containers. I've owned, cared for, or driven several vehicles over the years:
All cars, no matter how big or small, take 90% of the gallon, leaving me with just enough spare fluid that I don't want to throw it away. I end up with a mostly-empty gallon I have to lug around in the trunk until I have room for the rest. For over a decade, I've thought maybe the auto industry would fix this issue. My newest vehicle, the Chevrolet Venture, is a van. Having the most windshield real estate I've ever had, I thought, maybe this once I can fit a whole gallon... Nope!
I have a novel, not-so-genius idea for the automobile industry: Either automobile makers should include a full gallon-sized wiper fluid reserve, or wiper-fluid makers should distribute their fluid in a slightly smaller quantity.